The present invention relates to a method and apparatus for controlling the combustion produced in an internal combustion engine in accordance with the rotational speed of the engine, and more particularly the invention relates to such method and apparatus well suited for digitally calculating the amount of fuel supply and the like related to the combustion of the engine.
Conventionally, methods and apparatuses are known in the art, such as, disclosed in the U.S. Pat. No. 3,969,614, in which the amount of fuel supply and the spark ignition timing related to the combustion in an internal combustion engine are controlled by a digital computer. In accordance with a known method of this type, the number of times that the amount of fuel supply is computed for every revolution of the engine (every crankshaft revolution) is fixed irrespective of the rotational speed (the number of revolution or rotational frequency) of the engine, and the number of calculations correspond to the number of times fuel is supplied in accordance with the results of the calculations. However, in consideration of the fact that the rotational speed of the engine changes from the lower range speed to the upper range speed which is ten times or one hundred times the lower range value, at high speeds the time allowed for calculations (the time period of one engine revolution) is decreased thus causing successive calculations to tend to become closer with each other. In particular, where not only the amount of fuel supply but also the spark ignition timing are calculated by the digital computer, the time required for making the necessary calculations is increased proportionately thus making it extremely difficult to complete all of the required calculations for every revolution of the engine at the high speed operation of the engine.